Wednesday, December 1

More than 460 species of birds have disappeared due to human hunting in the last 50,000 years


A new study from Tel Aviv University and the Weizmann Institute found that, between the past 20,000 and 50,000 years, birds have suffered a major extinction event primarily inflicted by humans, reported in a release.

This extinction event, which occurred in the last phase of the Pleistocene, caused the disappearance of between 10% and 20% of all bird species, according to the researchers. The vast majority of extinct species shared several characteristics: they were large, lived on islands, and many of them did not fly.

The study, led by Shai Meiri and Amir Fromm, and published in the Journal of Biogeography, conducted a comprehensive review of the scientific literature and, for the first time, collected quantitative data on the number and characteristics of extinct bird species throughout the world.

Those that became extinct in the last 300 years are relatively well known, while earlier species are known to science from remains found at archaeological and paleontological sites around the world.

In total, the study listed 469 species of birds that became extinct in the past 50,000 years, although the researchers believe the actual number of species of birds that disappeared is much higher.

Hunter humans

Hunter humans Researchers think that the great extinction was caused mainly by humans hunting birds for food, or also by animals brought to the islands by humans, which in turn fed on birds or eggs.

This assumption is based primarily on two facts, the researchers explain: First, most of the bird remains were found in places inhabited by humans, apparently belonging to species consumed by their inhabitants.

Second, in most cases, the extinctions occurred shortly after the arrival of humans to the sites where these species inhabited.

The researchers also found that the extinction was not random, as most extinct species shared prominent characteristics.

Around humans

Around humans Approximately 90% of the extinct species in that period lived on islands. When humans arrived on these islands, the birds were either hunted by them or were victims of other animals introduced by humans, such as pigs, rats, monkeys and cats.

Also, most extinct bird species were large, some even very large. Consequently, since each bird provided humans with a large amount of food, they were a preferred target for hunters.

In fact, the body mass of extinct species was found to be up to 10 times greater than that of surviving species.

Previous studies had found a similar phenomenon among mammals and reptiles, especially lizards and turtles that lived on islands: the largest were hunted by humans and became extinct.

Finally, a large part of the extinct bird species did not fly and often could not escape their pursuers.

The study found that the number of flightless bird species that became extinct is twice the number of flightless species that still exist today: in total, 68% of the flightless bird species known to science became extinct .

One of the best-known examples is the moa bird in New Zealand: 11 species of moa became extinct in 300 years, due to hunting by humans, the study highlights.

Less diversity

Less diversity According to the researchers, this study shows that, before the greatest extinction event of the last millennia, many more large birds, even giant and flightless, lived on our planet, and that the diversity of birds that lived on islands was much greater than in the actuality.

The researchers hope that their findings will serve as red flags for bird species that are currently also in danger of extinction, noting that it is important to check if they have similar characteristics to those that have already disappeared.

However, they clarify that conditions have changed compared to the period analyzed and that, at present, the main cause of the extinction of species by humans is not hunting, but the destruction of natural habitats.

The Pleistocene corresponds to the Paleolithic stage of human development, when the way of life was hunter-gatherer: it allowed them to get food, clothing, firewood and materials for their tools and cabins.

Previous studies have considered that the expansion of human populations that occurred then exerted special pressure on large mammals, which were exterminated by excessive hunting. The new study quantifies the impact of this expansion on bird species.

Reference

Reference Big, flightless, insular and dead: Characterising the extinct birds of the Quaternary. Amir Fromm, Shai Meiri. Journal of Biogeography, 03 July 2021. DOI:https://onlinelibrary.wiley.com/doi/full/10.1111/jbi.14206

Top image: Bird species in the Zoological Garden. CREDIT: Tel Aviv University.


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